White Sands footprints suggest humans experienced abrupt environmental shifts during the last ice age
Expanded excavations at White Sands National Park in New Mexico have provided researchers an opportunity to refine the age of the oldest human footprints in North America and establish a deeper understanding of the landscape and environmental conditions at the time humans were present there.
New excavations at White Sands National Park in New Mexico have allowed scientists to better understand the age of the earliest known human footprints in North America and the environment during their presence. Published in Science Advances, the study led by the University of Arizona, the US Geological Survey, and other partners reveals that these ancient humans experienced rapid changes in temperature and water availability over their lifetimes.
The research team previously confirmed these footprints as the oldest evidence of human presence in North America, dating back between 23,500 and 21,700 years ago during the Last Glacial Maximum. Using refined excavation techniques and radiocarbon dating, the researchers determined the site's age, which enabled a deeper investigation into the abrupt environmental shifts early humans in North America faced.
The unique sedimentary record at White Sands allows for the reconstruction of climate and environmental conditions at an unprecedented temporal resolution, capturing fluctuations relevant to the humans and wildlife present at the time. The study shows that the climate at White Sands was highly dynamic, with the landscape transforming from conifer forest to sagebrush and oak steppe, and the massive Lake Otero receding.
By analyzing isotope signatures in preserved plant material, the researchers discovered significant swings in water availability within a century, including severe aridity during an abrupt warming event also documented in Greenland ice cores. This indicates that local aridity changes at White Sands mirrored global climate shifts.
During the Last Glacial Maximum, when humans left their footprints, temperatures in the Southwest were generally cooler, around 50°F (10°C), compared to today's annual mean temperatures of 60°F (16°C). The sudden vegetation shift from pine forest to pinyon and juniper occurred within approximately 100 years, with varying Ruppia pollen indicating fluctuations in Lake Otero's water levels over about 1,500 years.
These findings provide a rare glimpse into the environmental conditions and changes experienced by early humans and other megafauna in the Southwest, offering valuable insights into the region's complex climate history.
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